Hydropneumatic power unit



April 7, 1942;. w, B REED 2,279,057

HYDROPNEUMATIC POWER UNIT Filed April 16, 1938 Warren B.Reed 3 theoperating system.

Patented Apr. 7 1942 HYDBOPNEUMATIC POWER UNIT Warren B. Reed, NewOrleans, La.

Application April 16, 1938, Serial No. 202,440

BClaims.

My invention relates to a process for operating deep well reciprocatingpumps.

It is an object of the invention to provide a process of pumping deepwells whereby'the en- 1 ergy employed in'operating the devices thereformay be conserved and economized.

It is a further object to provide a device of maximum flexibilitywhereby the variation of the length of stroke may be changed by varyingthe relative gas pressures used in the system.

It is a further object to provide a process whereby a pump unit may beoperated by hydro-. pneumatic means and the force of the falling pumprod and plunger may be employed in generating and storing pressure to bereturned to It is another object to provide a flexible means operatingthe pump rod whereby the moving parts are pressure pontrolled at alltimes and thereby the wear and tear on the rod string be reduced to aminimum.

In the drawing herewith, Fig. l is a side view partly in elevation andpartly in central longitudinal section illustrating a preferred form ofmy invention.

Fig. 2 is a top plan view partly in section. Incarrying out my inventionI desire to operate the pump rod or other load reciprocating meansthrough the use of hydraulic means, supplemented by pneumatic pressureemployed therewith. In accomplishing this inventive idea I have provideda pump rod I which reciprocates within the well casing 2 and may beunderstood as having connected to it at the lower end thereof the usualoilpu'mp plunger and valve equipment.

The pump rod which is connectedto the piston rod carries at its upperend projecting above the platform! of the power unit a piston l. Saidpiston is formed with an outer cup shaped rim- 5 projecting upwardlyabove the body of the piston. On the lower end of said pistonis adownthe cylinder I in'which it reciprowardly extending hub 8' spacedsomewhat from is an upwardly extending rim or cup It. The interior ofsaid cup provides a space I5 about the rod into whichflts the hub 6 uponthe plunger.

The upperend of the cylinder has a closed extension l6 thereon whichforms a compression chamber closing the upper end of the cylinder Saidextension is connected with the cylinder by a special coupling member Hwhich has a central passage l8 the'rethrough, the lower end of which hasa downwardly extending flange is which is shaped and formed to fitwithin the upper cup shaped end 5 of the piston. I have further providedin connection with the coupling l1 and extension I6, a laterallyextending pipe 28 through which the charge of gas under pressure andalso oil may be injected into the cylinder and which v may have thereona pressure gauge 2 I. A quantity of oil 53 is injected into the cylinderthrough extending pipe 20 to ride above. the piston to act as alubricant also to facilitate the seal about the piston, but specificallyto provide fluid for a retarding action when the piston extension 5enters the space between the extending flange IQ of v the stop member I!and the cylinder wall to provide an hydraulic cushion and stop at theupward extremity of the piston travel.

The piston is adapted to be forced upwardly to operate the power unitand further compress the air volume above the piston through liquidforced into the cylinder below the piston through a pipe 22. Said pipeis connected to the side of the base member at 23. t

I have also shown an upwardly extending vent member, having-therein ahand operated valve 24, this vent to be used when the conductor pipesare being initially filled with oil.

My apparatus includes a pair of tanks or containers 25 and 26. The tank25 maybe called a power reservoir and the tank 26 a recovery tion ofeach container is filled with gas or air' under-a determined individualpressure. Each tank has, alaterally extending pipe thereon controlled bymeans of a hand valve 28 to be used when charging the tanks with air orgas under inder which is threaded at H! to'receive a threaded bushingII. This bushing has an axial opening therein through which the pistonrod may I reciprocate..; n box comprising packing l2 and a glandi3'thereon forms a; seal around the moving rod. At the upper end oi. thebushing and spaced slightly from the walls of the cylinder pressure.From the power reservoir 25 a pipe 29 is extended toward the power unitfor connection beyond the valve units at 30 with thepipe 22. A similarpipe 3i connects thereservoir 26 with said pipe 22. This pipe 22 may beonly a few feet as when the installation is at the derrick side or itmay be at any economic distance as in the "case of central control.

the housing 32 and has an opening 36 to be,

brought into registration with the passage 33 and an opening 31 to bebrought into registration with the passage 34. These two openings 36 and31 form two valves at right angles to each other so that when one valveis open the other will be, closed. Said valve member 35 is shown withextended rod 36 which may be operated by a motor 39 through a gearreduction means '40. Through this operating means the valve member iscaused to rotate with a predetermined, uniform, continuous and slowspeed which times and controls the number of strokes per minute of thepower unit.

The valve unit control of the power unit operation, its timing perstroke and number of strokes per minute is actuated independently of anyother function of the process.

The valve unit is so operated that one valve opens and closes at auniform speed with or without a closed interval of determined lengthbefore the other valve opens and then closes with the same uniformityfollowed by an optional closed interval. The uniform speed of the valvesin opening and closing causes the gradual enlargement from a smallbeginning to full orifice and then with gradually decreasing orifice tocomplete closure prevents the sudden jerk and jar due to aninstantly-applied and cut-off force, as is the case when quick openingand closing valves are used, and forms an important feature of controlin conjunction with the gas pressure operation of my invention. Theseclosed-intervals may be of the same length or the intervals may bevaried-by -design of the valve opening so that at the top of the strokethe interval may be short and at the bottom of the stroke it may have alonger interval. This closed interval or dwell in the stroke allows timefor the stretch in the rods to be taken up at the end of the up-strokebefore the down stroke begins, and also allows for the stretch of therod as the upstroke begins.

The valve design may be of the slide valve, piston valve,rotary valve orother variation and the valves may be actuated in many ways and byvaried power means without departing from the principles of myinvention.

The recovery reservoir and the power reservoir are connected to eachother through a pump 4i. An outlet pipe 42 from the recovery reservoir-26 is connected to the inlet side or suction of said pump. In the pipe42 is placed a check valve 4.3 allowing the passage of liquid in thedirection of the arrow. Between the pump'4l and the power reservoir 25is the pump discharge pipe 44 having therein a check valve 45 opening inthe direction of the reservoir The pump 4| is shown operated from thepower shaft 46 of the electric motor 41. Said motor is governed througha rheostat and control switch 48 operated by pressure from-the powerreservoir 25 through a connecting pipe 49. It will be understood thatchanging pressure in the reservoir 25 will regulate the motor speedwithin set limits and will further actuate a switch in the controlchamber 46 to start and -stop the motor when the pressure rises above orfalls below established limits. In this manner the amount of liquidpumped can be controlled and the determined gas pressure maintained.This type of regulat r is operating the vent 24.

part of the motor equipment and can be purchased in the market. If gas,gasoline or Diesel type engine be used as motive power the regulationthereof will be controlled by changinB' pressures in power reservoir 25through means of diaphragm regulators.

Supply of oil for the circuit is introduced and adjusted through theinlet pipe 50 having thereon the recovery reservoir and the powerreservoir andmay be used to indicate the pressure in either of saidreservoirs by the proper manipulation of valves in the pressure line inwhichthe gauge is set.

To introduce the various air pressures the valve units are closed andthrough valve 23 air is injected into the power reservoir 25 of adetermined initial pressure Pl. This pressure will be exerted from checkvalve 45, tank 25, pipe 29, to

the closed valve 31 in the valve unit. In the power unit cylinder withthe piston in down position an initial pressure Cl is introduced throughpipe 20. This pressure extends through pipe 22 to the closed valves 36and 31 in the valve unit. In like manner an initial pressure RI isintroduced into the recovery tank and extends from closed valve 36 inthe'valve unit, the recovery reservoir and thence through pump 4| tocheck valve 45. vidual air pressures are of such relation and differencethat by operating the valve unit which puts thenyin motion and the powerdriven pump which restores the pressure in the power reservoir thesystem functions as designed.

With the initial air pressures as described, the detail of a completecycle will be as follows:

A part revolution of valve member 35 would open valve 31 (with valve 36closed). The pressure PI of the power reservoir would then extend to thepower unit, forcing the piston therein to its up position, lifting theload on the piston rod and compressing the initial ,air pressureC I intothe chamber 16 with a resulting increased pressure C2. Duringthis'upstroke a volume of oil VI has been forced by the expandingpressure Pi into and filling the power unit cylinder from the base tothe piston in the up position. The

expansion by the transfer of this volume VI from power reservoir topower unit cylinder has reduced the pressure of PI to P2 and increasedthe pressure of CI to C2. The up position is therefore reached at thepoint of equilibrium of the resultant of pressure P: and C2. It isobvious that this point of equilibrium and stop may be varied byadjusting initial pressures P1 and/or 01 piston, forcing the oil volumeVI below the piston through pipe 22, valve 36, pipe 3| into the Thesethree determine'dindi The valve unit 31 individual values are so fixedand utiliaed in relation to the determined initial pressure in therecovery reservoir 25 and compressing its pressure Rl by the amount ofoil VI to an increased pressure R2. This increasing compression of .Rl

to R2 during the down progress or the piston tends to retard the downvelocity of the piston and back pressure R2 which is so determined thatit equalizes the gravity load on the piston plus the expanding pressureC2 increasingly retarding the piston travel until brought to a stop atsome determined point above the lower hydraulic stop provided in thebase member. At the end of the down stroke the pressure R2 extends fromthe piston through the valve unit into the recovery tank until valve 36is closed when .this

pressure R2 is separated by the closing of said valve. We then have thecylinder pressure reduced to C l and recovery reservoir with pressure R2and a power reservoir with pressure P2.

It is now the function of the power driven pump II to pump oil volume VIat pressure R2 from recovery reservoir into the power reservoir,

returning to it oil volume VI to recompress this pressure P2 back to theinitial pressure Pl, thus completing one cycle. This detail with themodification that the power driven pump action is continuous describesone complete cycle.

In the operation of my power unit equipped with fluid under determinedinitial pressure within the power reservoir 25 which will be sufficientto raise the rod load attached to the piston 4,

the pump plunger and the load of liquid above sure of the gas in theupper end'of the cylinder and extension IE will cause the piston to movedownwardly, and theoil below the piston will be forced out through thepipe 22 and through the valve member 35 into the recovery cylinder 26.It will there buildup a back pressure sufllcient said piston when saidpiston exceeds its normal to slow down the dropping of the piston untilequilibrium and stop is reached at some deterv mined point, where itwill remain until the valve member 35 is rotated sufllciently to closepassage 33 and openpassage 34. The force of the falling piston and itsload will compress the gas or air within the recovery cylinder and thusstore up pressure. The energy of this stored up pressure is conserved byassisting the pump Al to move the liquid therein back to the powerreservoir 25 to maintain the pressure in said reservoir at thepredetermined amount. 7 4

Another advantage of my process which is now obvious is that the strokeof the plunger may be lengthened or shortened as desired by theincrease. or decrease of the coordinated gas pressures. An increase inthe initial pressure in the power unit cylinder will decrease the lengthof the upstroke. An increase in the. initial pressure of the powerreservoir would increase the length of the upstroke. An increase-in thein itial pressure of the recovery reservoir will shorten the downstrokewhile a decrease in this pressure would permit a longer downstrokebefore an equilibrium and stop is reached. It is also obvious that thedetermined initial pressures in power and recovery reservoirs are morethan a lifting and counter compression means, as their determinedthereby.

cylinder in the power unit that the length of both the up and downstroke is controlled and Under normal operative conditions the speed ofpiston travel is adjusted to coincide with the opening and closing ofthe valves. When, however, the normal adjustments are thrown out ofbalance the valves may close and stop the piston travel before thenormal stroke is ended, or the pistonmay have completed its stroke toawait the closing of its valve.

It is also obvious that a change in the gravity load on the piston willchange an established equilibrium thereby afl'ecting the length ofstroke. The well gassing or. starting to flow, or

a break in the rod string will all lighten the load and extend thelength of stroke upward probably beyond pressure control. On the otherhand an undue loss of pressure in the recovery reservoir will lengthenthe down stroke. It is ,to take care of such abnormal changes, sudden orotherwise, that the hydraulic stops at the upper and lower end of thecylinder are pro- 25' vided to decrease shock'and bring th ascending ordescending piston to a safe aulically emergency cushioned stop. Byvariation of the speed of. rotation of the valve member 35 the timebetween the upward and downward stroke may also be controlled toaccomplish the speed of operation which is adapted to any particularpumping installation. The operation of the power driven pump iscontinuous at almost fixed loadand uniform speed with consequent highefliciency for both pump and motive power and with minimum wear. Furtheradvantages of the invention will be obvious td those skilled in the art.

WhatI claim is new'is:

l. A reciprocating motor including a cylinder, a piston therein, atubular stop member in said cylinder to positively limit the upwardmovement or said piston therein, a cup shaped upper end on said pistonadapted to contain a liquid, a sleeve-like projection extendingdownwardly from said stop member adapted to engage in upward travel andthus "act as a shock absorber, a chamber for air under pressure abovesaid stop member, means alternately to introduce into and exhaustpressure fluid from said cylinder below said piston, and means wherebythe pressure of fluid in said chamber may be varied to oppose and stopthe upward movement of said piston in said cylinder.

2. In a power unit of the character described for wells, a powerreservoir, a recovery reservoir, said reservoirs having gas and liquidunder individual pressures therein, a pump to transfer liquid from saidrecovery reservoir to said power reservoir to maintain the desiredpressure in said power reservoir, a pipe connection between saidreservoirs and a pressure fluid operated mosaid reservoirs having gasand liquid under mdividual pressures therein, a pump to transfer a tweensaid reservoirs and a pump operating device, and means to operate avalve in each of said.

pipe connections to control the flow or fluid pressure to saiddevice toperiodicallyopen and close one valve from said power reservoir to saiddeviceand after a determined time intervalto open and close the otherwith a determined time interval thereafter before repeating the cycle.

4. In a power unit or the character described, a hydraulically operatedmotor for a well pump, a fluid pressure power reservoir, a recoveryreservoir, said reservoirs having gas and liquid under individualpressures therein, a pump to transfer liquid from said recoveryreservoir to said power reservoir to maintain a-predetermined pressurein said power reservoir, pipe connections between said reservoirs andthe intake of said pump motor, a valve member in said pipe connections.a power means to continuously operate said valve member to periodicallyopen and close one valve in the line from said power reservoir to saidmotor and then open and close the other in the exhaust from said motorwith a time interval between the opening and closing of each valve.

5. In combination, a motor cylinder, a load engaging piston therein, areservoir for liquid under a determined gas pressure to raise saidpiston and its load, a recovery reservoir to receive the exhaust liquidfrom said cylinder, said recovery reservoir having gas under determinedpressure therein to oppose and finally stop the descent of said pistonat a determined point in said cylinder, a gas containing extension onsaid cylinder having gas under pressure therein sufficient to oppose andfinally stop the power stroke at a determined point in said cylinder,and means to control the passage of fluid. to and from said cylinder.

6. In a hydro-pneumatic power unit, a cylinder, a. piston thereinadapted to reciprocate an attached gravity load, said cylinder having agas volume under determined initial pressure above said piston, means toadmit liquid under a determined expanding gas pressure below said pistonto force the piston upward thereby compressing the said gas volume abovesaid piston to increasingly retard the upward travel of said piston to apoint of balance and stop at a determined point in said cylinder, meansin turn to discharge the liquid under said piston with its descendingload and expanding pressure, said discharge liquid compressing a gasvolume under initial determined pressure to increasingly retard thedownward piston travel to a determined point of balance and stop, andmeans to maintain the said individual gas volumes and pressure at theirdetermined relative values.

WARREN B. REED.

